Abstract: Two-dimensional (2D) functions with wallpaper group symmetry can be written as Fourier series displaying both translational and point-group symmetry. We elaborate the symmetry-adapted Fourier series for each of the 17 wallpaper groups. The symmetry manifests itself through constraints on and relations between the Fourier coefficients. Visualising the equivalencies of Fourier coefficie...

We present a novel approach to investigate the properties of diffusion weighted magnetic resonance imaging (dMRI). The process of restricted diffusion of spin particles in the presence of a magnetic field is simulated by an iterated complex matrix multiplication approach. The approach is based on first principles and provides a flexible, transparent and fast simulation tool. The experiments car...

We propose a novel feature vector suitable for searching collections of 3D-objects by shape similarity. In this search a polygonal mesh model serves as a query. For each model feature vectors are automatically extracted and stored. Shape similarity between 3D-objects in the search space is determined by finding and ranking nearest neighbors in the feature vector space. Ranked objects are retrie...

We consider a topological integral transform of Bessel (concentric isospectral sets) type and Fourier (hyperplane isospectral sets) type, using the Euler characteristic as a measure. These transforms convert constructible Z-valued functions to continuous R-valued functions over R n. Core contributions include: the definition of the topological Bessel transform; a relationship in terms of the lo...

In this paper ,the general solution of steady-state one dimensional asymmetric thermal stresses and electrical and mechanical displacements of a hollow cylinder made of functionally graded material and piezoelectric layers is developed .The material properties ,except the Poisson's ration, are assumed to depend on the variable radius and they are expressed as power functions of radius. The temp...

In this paper we introduce convolution theorem for the Fourier transform (FT) of two complex functions. We show that the correlation theorem for the FT can be derived using properties of convolution. We develop this idea to derive the correlation theorem for the quaternion Fourier transform (QFT) of the two quaternion functions.

Abstract. The shape of wheat kernels is one of the most important criterions for quality inspection and grading. This paper has used Fourier describer to describe the three views of wheat shape accurately and has had a counter-construction operation.Also it verified this method for describing the shape, small but complex. Finally, the appropriate characteristic parameters were selected, and the...

In this paper we apply a method of spectral theory of linear operators [10] to establish relations between the support of a function f on R with properties of its image Tf under a linear operator T : R → R. The classical approach uses analytic continuation of the image Tf into some complex domain (theorems of Paley-Wiener type [4, 5, 6, 7]), and therefore, could not apply to functions whose ima...